montmorilloniitti

Montmorillonite is a clay mineral belonging to the smectite group. It is a phyllosilicate, meaning its structure is composed of layered sheets of silicate tetrahedra and octahedra. The general formula for montmorillonite is (Na,Ca)0.33(Al,Mg)2(Si4O10)(OH)2·nH2O. Its defining characteristic is its ability to absorb and hold water, causing it to swell significantly. This swelling is due to the presence of interlayer cations that can be easily exchanged for water molecules. The crystal structure of montmorillonite consists of repeating layers of two tetrahedral sheets sandwiching one octahedral sheet.

Montmorillonite is typically white to pale yellow or green, but its color can vary depending on impurities. It is a soft mineral with a waxy or earthy feel. It forms through the weathering of volcanic ash and other magnesium- or aluminum-rich rocks. It is commonly found in sedimentary rocks and soils. Its high cation exchange capacity and swelling properties make it useful in a variety of applications.

Industrially, montmorillonite is used as an absorbent, a binder, a rheological modifier, and a filler. It is a key component in drilling muds, where its swelling helps to seal the borehole and suspend cuttings. It is also used in cat litter, cosmetics, pharmaceuticals, and as a binder in animal feed. In environmental applications, it is used for landfill liners and in the remediation of contaminated sites due to its ability to adsorb pollutants.